The 18-year-old had just teed off at 16 on Sunday when the horn sounded to halt the round because of darkness and, despite having the option to complete the hole, she chose to mark her ball on the fringe at the green instead.
Lee, who turned professional in September, then shook off a three-putt bogey on her first hole on Monday morning and finished with two pars for a 6-under 65 and 15-under 269 in total.
It was her first title as a professional as she became the seventh LPGA Tour player to win before her 19th birthday.
“I didn’t think this moment would come this year, so I’m stoked to have won,” she said after signing autographs behind the 18th green while waiting to see if her lead would be enough.
“Just because I won in my rookie season, I feel like I could probably do it again. It just kind of gives me confidence that I can play out here and win out here.”
Lee surged into the lead on Sunday thanks to a five-hole stretch that she played in 5-under before darkness halted play. She returned to the Kingsmill Resort’s River Course early Monday with a four-stroke lead.
Having marked her ball about 15 feet from the hole on Sunday night, Lee proceeded to three-putt for bogey but managed to make two pars to complete her round.
She became the third rookie to win this year and earned $195,000 (??124,350).
So Yeon Ryu started her day with three consecutive birdies and finished second, with Alison Lee another shot back.
“Sometimes early morning my body is still not awake, but this morning my body condition was even better than yesterday,” Ryu said. “So I pretty much made every shot and every putt. So, yeah, perfect this morning.”
Alison Lee, who started on the par five 15th, made a birdie after Minjee Lee’s bogey, trimming her deficit from four strokes to two. But her approaches at 16 and 17 left her long putts, neither of which fell, and she made bogey at 18.??
“On 16 and 17, I felt like I hit two good putts, but they didn’t go in,” the 20-year-old said. “And on 18, I just kind of gave up on myself and I shouldn’t have done that. I should have finished strong.”
Both Lees were due to play in a U.S. Open qualifier on Monday with Minjee Lee qualifying with her victory. Alison Lee, however, forfeited her spot and planned to try to get into a qualifier in California on Tuesday.
Perrine Delacour of France, the leader entering the final round, closed with a 71 and finished fourth. Top-ranked Lydia Ko tied for 16th at 5-under.